The present invention relates to a pressure sensor that is capable of detecting a pressure such as a cylinder internal pressure in an internal combustion engine, and more particularly to a pressure sensor that has a plate-shaped Si device for detecting the pressure, which is an object of detection, and a pressing member that is bonded to one main surface of the Si device and presses the main surface by a pressing force according to the pressure.
In recent years, as a pressure sensor that is capable of detecting a pressure P such as a cylinder internal pressure in an internal combustion engine, there have been proposed and developed various pressure sensors having a Si device for detecting the pressure P through a stress that occurs to the Si device itself according to the pressure P by piezoresistive effect. One such pressure sensor has been disclosed in Japanese Patent Document 1 (Patent No. 3317084, see the following Related Art Documents). In Patent Document 1, the pressure sensor has a plate-shaped Si device and a pressing member. The pressing member is bonded to one main surface of the Si device, and presses the main surface by a pressing force according to the pressure P.
A force transducer in Patent Document 1 has a silicon single crystal (Si device), a pressure transfer block (pressing member) that is bonded to (100) plane of the silicon single crystal, and a base (supporting member) which is made of glass-ceramic and bonded to the other main surface of the silicon single crystal (see FIG. 1 and its description in Patent Document 1). The pressure transfer block is made of glass-ceramic and serves to transmit a pressing force, which is applied to an opposite surface to the semiconductor crystal side, to the semiconductor crystal. On the (100) plane of the silicon single crystal, a square ring-shaped gage (resistor) that arranges a bridge and lead members that connect with the gage are formed. The gage, a part of each lead member and the pressure transfer block are bonded together through electrostatic bonding, then the silicon single crystal and the pressure transfer block are bonded together.
As the pressure sensors having the plate-shaped Si device and the pressing member bonded to the main surface of the Si device, they have been disclosed in the following Japanese Patent Documents 2˜6.
(Related Art Documents)
    Patent Document 1: Japanese Patent No. 3317084    Patent Document 2: Japanese Patent Provisional Publication No. 7-83129 (hereinafter is referred to as “JP7-83129”)    Patent Document 3: Japanese Patent No. 3166015    Patent Document 4: JP7-14069    Patent Document 5: JP6-54274    Patent Document 6: Japanese Patent No. 3116384